So what is stopping us? According to the latest study by Judit Lienert and Tove Larsen, not much!

Not much?
Other than almost all waist coming out of homes and business’ leave the building by one pipe. Now it’s hard enough to get cities to do sewer separation ( my city alone has been at it for 2 decades, is well over budget and still has a couple more decades of work yet to do ) try and get them to lay a second pipeline for waste.

Now is you are building a whole new community, laying new pipeline or not being connected to begin with, sure. Otherwise the infrastructure change would be hell.

Look how long it’s taken electric cars and they’ve been around since the beginning of the automotive race.